Improvement: function cut

Hello Andrew,


But "cut" generates factors. In most cases with real data one expects to
have also the ends of the interval: the argument "include.lowest" is both
ugly and too long.

[The test-code on the ftable thread contains this error! I have run
through this error a couple of times.]


The only real situation that I can imagine to be problematic:

- if the interval goes to +Inf (or -Inf): I do not know if there would be
any effects when including +Inf (or -Inf).


Leonard


On 9/18/2021 1:14 AM, Andrew Simmons wrote:

While it is not explicitly mentioned anywhere in the documentation for
.bincode, I suspect 'include.lowest = FALSE' is the default to keep the
definitions of the bins consistent. For example:


x <- 0:20
breaks1 <- seq.int(0, 16, 4)
breaks2 <- seq.int(0, 20, 4)
cbind(
    .bincode(x, breaks1, right = FALSE, include.lowest = TRUE),
    .bincode(x, breaks2, right = FALSE, include.lowest = TRUE)
)


by having 'include.lowest = TRUE' with different ends, you can get
inconsistent behaviour. While this probably wouldn't be an issue with
'real' data, this would seem like something you'd want to avoid by default.
The definitions of the bins are


[0, 4)
[4, 8)
[8, 12)
[12, 16]


and


[0, 4)
[4, 8)
[8, 12)
[12, 16)
[16, 20]


so you can see where the inconsistent behaviour comes from. You might be
able to get R-core to add argument 'warn', but probably not to change the
default of 'include.lowest'. I hope this helps


On Fri, Sep 17, 2021 at 6:01 PM Leonard Mada <leo.mada at syonic.eu> wrote:

Thank you Andrew.


Is there any reason not to make: include.lowest = TRUE the default?


Regarding the NA:

The user still has to suspect that some values were not included and run
that test.


Leonard


On 9/18/2021 12:53 AM, Andrew Simmons wrote:

Regarding your first point, argument 'include.lowest' already handles
this specific case, see ?.bincode

Your second point, maybe it could be helpful, but since both
'cut.default' and '.bincode' return NA if a value isn't within a bin, you
could make something like this on your own.
Might be worth pitching to R-bugs on the wishlist.



On Fri, Sep 17, 2021, 17:45 Leonard Mada via R-help <r-help at r-project.org>
wrote:

Hello List members,


the following improvements would be useful for function cut (and
.bincode):


1.) Argument: Include extremes
extremes = TRUE
if(right == FALSE) {
    # include also right for last interval;
} else {
    # include also left for first interval;
}


2.) Argument: warn = TRUE

Warn if any values are not included in the intervals.


Motivation:
- reduce risk of errors when using function cut();


Sincerely,


Leonard